. >> reporter: after leaving the navy in 2009, he started a security company in his native texas. it was on a shooting range 50 miles out of fort worth that kyle and chad littlefield were shot to death. a former marine arrived with them and killed them with a semiautomatic handgun recovered at his sister's house and confessed to the murder before returning home. >> around 9:00 p.m. they spiked his tires. the vehicle was stopped, and he was apprehended without any scuffle or fight. >> reporter: the sheriff says his understanding is that ralph may suffer from mental problems related to his military service but offered no specifics or possible motive. much of kyle's time in iraq was spent providing sniper cover for u.s. troops in some of the war's most intense urban battles. >> every person i killed i have a clear conscience of, because they were actively trying to harm americans, allies or civilians. >> reporter: his skills earned him a reputation with insurgents. >> they put a bounty on your head. >> reporter: they did. you make it through four, five tours in combat and he comes ba